Optical transceivers mass produced using integrated circuit techniques are adversely affected by process variation and inter-chip thermal drift of component optical properties. Process variation is a random process appearing as a random walk when, for example, devices near each other (on the same wafer) have similar characteristics but devices located some distance away (on the same or on a different wafer) have notably different characteristics.
Continuously increasing demand for telecommunications bandwidth has driven development of optical fiber systems that include optical transmitters and receivers. These optical devices are implemented in smaller and smaller systems, including data communications, inter-chip optical interconnections in information processing systems, and even intra-chip optical interconnections in multicore optical processors. The need for miniaturization of transceivers is an overriding issue, and is typically addressed through monolithic component integration.
Optical wavelength division multiplexing (WDM) allows for increased carrying capacity of optical fibers and other optical waveguides. This increase is achieved by employing a number of channels widely spaced (in wavelength) such that optical filters perform channel separation. Such filters may be employed in the optical domain before detection and optical-to-electrical signal conversion.
Temperature variations challenge WDM processes within integrated optical components and the narrow-band laser sources coupled thereto. For example, in an integrated optical component including four modulators each receiving an optical signal from a different laser, temperature variation alters the source laser wavelength which in turn degrades performance of the integrated optical component. Laser athermalization techniques have attempted to mitigate this but only at the great expense of increased cost, power and size.